| 摘要 |
PURPOSE:To easily set up F treatment stabilized operation conditions by adding a substance containing chlorine to raise up calcium index more than corresponding to the concentration of flourine allowable in treated drain. CONSTITUTION:Exhaust gas desulfurized drain 21 containing F, SO4, heavy metal and the like is guided into rough neutralization process 1, pH being adjusted at 2-4 with slaked lime 31 and mineral acid 32, and SO4 in waste water is separated as CaSO4 and 2H2O. At the same time, metal hydroxide in aggregated sedimenting sludge 23 being sent back from aggregated sedimenting process 3 is solved again. Next, the same is led into pH adjusting process 2 and is adjusted at pH7-9 by adding slaked lime 31, and then F and AlF2<+> in drain are reacted to turn the same into hard soluble CaF2. Then, by grasping calcium index in drain, the concentration of dissolved Ca is maintained and a stabilized F treating performance is provided.
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